Question 17
The gas in an engine
does work on a piston of cross-sectional area 80 cm2. The pressure
on the piston has a constant value of 4.6 × 105 Pa.
How much work is done
by the gas on the piston when it moves through a distance of 25 cm?
A 9.2 × 102 J B 9.2 × 104 J C 9.2 × 106 J D 9.2 × 108 J
Reference: Past Exam Paper – June 2015 Paper 13 Q17
Solution:
Answer:
A.
For a constant pressure,
Work done = pressure × change in volume
Work done = p × ΔV
As the gas in the engine
does work on the piston, there is a change in volume.
ΔV = cross-sectional area ×
distance moved
ΔV = 80×10-4 ×
0.25 = 0.002 m3
Work done = p × ΔV
Work done = 4.6×105
× 0.002
Work done = 920 J = 9.2×102
J
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